The current emphasis among all countries to find cheaper and sustainable sources of renewable energy has had one of its most noticeable impact on the expanded use of wind turbines for the production of electricity. In the United States these wind turbines typically have a set of three large blades. The set of three large blades is attached to a device which converts rotational mechanical energy into electrical energy. The rotational mechanical energy is provided by the force of the wind against the set of three large blades. To maximize the conversion of wind energy to electrical energy, the structure used to support the set of rotating blades allows the entire set of rotating blades to turn with respect to the long, substantially vertical axis of the hollow tower to maximize the speed of blade rotation.
Positioning and supporting the set of large rotating blades and the associated equipment above the ground and in the path of prevailing winds is the large hollow tower. Within the large hollow tower are numerous pieces of equipment. This array of equipment is associated with the rotation of the blade set into the wind, the conversion of wind energy into electrical energy and the operational and performance monitoring equipment. The operational and performance monitoring equipment records information indicating both performance of the wind tower over time and any needs for maintenance or the replacement of key items. These key items located in the hollow tower must be maintained and, when necessary, replaced by maintenance and service technicians.
To facilitate the maintenance or replacement of equipment mounted within the hollow tower by maintenance and service technicians, multiple platforms or decks are positioned near where equipment is located. Formed within each platform deck within the hollow tower are openings. Specifically, in most hollow towers there is a hoist opening associated with each platform or deck for raising and lowering equipment to positions where the equipment within the tower may be serviced or replaced. Typically included within each deck is a ladder sized opening. The ladder sized opening enables the passage of a ladder therethrough. The ladder allows personnel within the tower to move to locations between the platforms or decks.
While a ladder may be sufficient for light maintenance work or the replacement of small pieces of equipment within the tower, there may be a need for something more substantial when large, heavy or unwieldy pieces of equipment must be maintained or replaced. Further, many equipment repairs performed by maintenance, service or repair technicians require the use of both hands. If a maintenance or service technician is on a ladder, then the use of both hands to work on equipment may be either impossible or dangerous. Further, OSHA safety requirements related to wind tower operation and maintenance may prohibit the completion of certain types of maintenance, service or repairs by technicians whose only support above a platform or deck is a ladder.
To meet the need for positioning a maintenance or service technician within a hollow wind turbine tower; particularly when it is necessary to service large, heavy or unwieldy pieces of equipment, some wind turbine operators have attempted to use cable hoisted man-lifts designed for use in a variety of above ground applications where the size of cable hoisted man-lift is not a pertinent consideration. These prior art man-lifts are typically attached to the top of the hollow tower and are moved vertically within the hollow tower by lifting cables. The lifting cables for prior art man-lifts may pass through openings in the platforms or decks within the hollow wind turbine tower.
Some of the prior art man-lifts are constructed in the form of a kit. The kit can be dismantled and then reassembled on each platform or deck within the hollow tower. When the maintenance, service or repair work has been completed by maintenance or service technicians in the space between the decks, the prior art man-lift kit is disassembled and moved, piece-by-piece up or down to the next platform or deck within the hollow tower. At the next platform or deck, the disassembled prior art man-lift kit is then re-assembled for movement between the next set of platforms or decks within the hollow tower.
Because the disassembly and re-assembly of prior art kit-type man-lifts takes time and risks injury to maintenance or service technicians from improper disassembly or re-assembly there is therefore a need in the art for a man-lift which can be easily passed through the openings in the platforms or decks without requiring the disassembly or re-assembly characteristic of prior art kit-type man-lifts.